Organic matter contribution to soil fertility improvement and maintenance in red Alder (Alnus rubra) silvopastoral systems

Abstract

An investigation was conducted to quantify fine roots and roots nodules over the four seasons in forestry and agroforestry alder (Alnus rubra) stands in North Wales. Soil samples collected in each season were excavated at three sampling points (0.30 m, 0.57 m and 1.00 m distance from the base of each tree) from nine trees of the agroforestry and forestry plots. Result showed that the density of live fine root had significant differences in between seasons and treatments (P < 0.001). The mean weight density of live fine root over the four seasons in agroforestry and forestry was 0.27±0.01 kg·m⁻³ and 0.54±0.03 kg·m⁻³, respectively. Weight density of dead root in each system remained constant throughout the year. The mean weight density of dead root was also significantly different (P < 0.01) between forestry and agroforestry systems. Weight density of live and dead root nodule was both constant throughout the year and between the different sampling distances. The mean weight densities of live and dead root nodule over the four seasons were 0.09±0.03 kg·m⁻³ and 0.05±0.03 kg·m⁻³ in agroforestry and 0.08±0.02 kg·m⁻³ and 0.03±0.01 kg·m⁻³ in the forestry plots, respectively.

Keywords

alder / Alnus rubra / root nodule / fine root / nitrogen